1. Field of the Invention
This invention relates to thermal protection of static and movable components in a 2-D reverser nozzle of a gas turbine, particularly during high temperature operation.
2. The Prior Art
Two dimensional (2-D) variable area exhaust nozzles for gas turbine engines are known in the art. See for example, U.S. Pat. No. 4,690,329 to Madden (1987), which patent is incorporated herein by reference. A 2-D nozzle is mounted in the aft end of a jet engine to modify and/or direct the jet blast exiting the nozzle within desired limits during flight, including redirecting such blast so as to provide reverse thrust to such engine.
Such prior art 2-D redirect or reverse thrust nozzle is similar to that shown in FIGS. 3 and 5 of the present application where the hot combusted gases 10 are directed rearwardly through tapering housing 12, between full-open nozzle flaps, such as flap 14a (in phantom) and out through divergent nozzle flaps, such as flap 16 (also in phantom) as indicated in FIG. 3. In the full open position, afterburner combustion can be applied to the hot gases 10 flowing toward the flaps 13 and 14, raising the temperatures of such gases therein to 4000.degree. F. or more, which temperatures are corrosive to (and/or melt) most metals. Accordingly, during such afterburner operation, it is important to thermally protect components such as flaps 13 and 14 and arc valve 15, when they become exposed to the above hot afterburner gases.
Further reviewing the prior art, with the afterburner shut off, the flaps 13 and 14 can be pivoted to narrow the exit throat 17 therebetween, as indicated in FIGS. 3 and 4 (e.g., to reduce thrust and save fuel). In such case, the arc valve, (e.g., valve 15) is now exposed by the pivoting of flap 14 and is subject to heating by the engine exhaust gases but remains closed so as to direct all such gases aft, along and between flaps 13 and 14 and then out rear nozzle flaps 18 and 20 as shown in FIG. 3. Subsequently, when it is wished to turn or reverse the direction of the exiting combusted gases, per FIG. 5, again with the afterburner shut off, flaps 13 and 14 are pivoted at near right angles to the oncoming gas 10, the arc valve 15 is now pivoted behind flap 14 and louvres 22 are opened so as to permit such engine gases to be turned by the closed flap valves 13 and 14 and redirected through the space previously occupied by the arc valve 15 and thence out through the open louvres 22, to provide reverse thrust and strong braking power to such engine 11.
The engine thus shown in the prior art is a workable 2-D reverser thrust nozzle. However, no discernable provision is made for thermally protecting certain components thereof from the corrosive effects of high temperature combustion gases particularly components such as the rotatable Wall support members for the flaps 13 and 14 and the arc valve 15, shown in FIGS. 3 and 5.
Other prior art makes provision for thermally insulating components for a convergent/divergent gas turbine engine exhaust nozzle, see U.S. Pat. No. 4,203,286 to Wharburton (1980). Such reference provides overlapping thermal shields for relatively static walls, which is not overly difficult but when as with the above 2-D reverser nozzle, certain functioning surfaces must pivot or rotate the attached shields or liners must do likewise, which can destroy the overlapped condition and expose the liner edges and/or underlying components.
It would seem one thing to provide overlapping liners for a static surface and a rotating surface but where there is a pair of concentric members which rotate in or next to a static surface, it would seem impossible to shield all edges at all rotated positions of both concentric parts along with the static surface.
Certainly there is no suggestion of how to solve such multi-liner problem in the above prior art. Accordingly, there is a need and market to provide a thermal shield or liner system for a plurality of rotating and static members that overcomes the above prior art shortcomings.
There has now been discovered a liner system that provides overlapping thermal shields for at least one static member or surface and a plurality of pivoting or rotating members proximate thereto, to thermally protect such members or components from corrosive combustion gases in a 2-D reverser nozzle of a jet engine, including during the afterburner operation thereof.